The statements in this section merely provide background information related to the present disclosure. Accordingly, such statements are not intended to constitute an admission of prior art.
Internal combustion engines include one or more intake valves controlling intake flow into a combustion chamber and one or more exhaust valves controlling exhaust flow from the combustion chamber. Valve control includes opening and closing the valves as various times during a combustion cycle. One known method to control valves includes a timed rotating camshaft, which by rotation of at least one non-circular cam displaces the valves from a closed condition to accomplish the desired opening and closing of the valves.
Almost all modern automotive engines have gone to flexible valvetrains for performance, fuel economy, and emissions reasons. Valve control in both magnitude, timing, and duration can greatly impact operation of the engine. A camshaft is only one method for controlling valve operation. Camshafts are somewhat limited in how much variation or flexibility a spinning cam can afford the valve operation. Camless systems provide flexibility, removing the limitations of the spinning cam from available valve control options.
Almost all engine manufactures would like the flexibility of camless valve control but avoid it for the following reasons plaguing all currently available systems: system cost, reliability and durability, package size, and parasitic losses.